Effects of Accumulated Damage on the Dynamic Properties of Coal Measures Sandstone

The coupling effect of accumulated damage and impact load substantially affects the integrity of the surrounding rock structure in deep coal mining engineering, which has inhibited safe and effective coal mining. Therefore, dynamic compression tests were performed on coal measures sandstone specimens with accumulated damage using the SHPB device. The effects of a high strain rate and accumulated damage on the sandstone's mechanical behavior and damage evolution were investigated. The results reveal that accumulated damage has a considerable impact on specimen stress-strain curves and lowers dynamic compressive strength and deformation modulus substantially. The sandstone failure mode looks to be shear failure from a macroscopic perspective, while it appears to be intergranular fracture between the mineral particles from a microscopic perspective. The macroscopic and microscopic failure mechanisms of the sandstone specimens likewise conformed to the energy absorption law. The accumulated damage factor and the accumulated damage correction coefficient were presented in order to construct a statistical damage constitutive model of rocks based on the Weibull distribution. This model provides a decent description of the effects of accumulated damage and the strain rate on sandstone's mechanical behavior, with parameters that are all of evident physical significance.

Automated summary

Dynamic compression tests were conducted on sandstone specimens to investigate the effects of accumulated damage and high strain rate on mechanical behavior and damage evolution. The results showed that accumulated damage significantly influenced the stress-strain curves, compressive strength, and deformation modulus of the specimens. A statistical damage constitutive model based on Weibull distribution was proposed to describe the effects of accumulated damage and strain rate on sandstone's mechanical behavior.